Methods for Regenerating Defective or Absent Myocardium

ABSTRACT

A method for treating damaged or diseased mammalian tissue that includes the steps of (i) providing a sheet structure formed from acellular dermal mammalian tissue that includes extracellular matrix (ECM) and a supplemental bioactive component, such as a nucleic acid, and/or a cell, and (ii) delivering the sheet structure to the damaged or diseased mammalian tissue, wherein the sheet structure induces angiogenesis and, thereby, regeneration of new mammalian tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application. Ser. No.16/990,350, filed on Aug. 11, 2020, which is a Continuation of U.S.application Ser. No. 15/902,063, filed on Feb. 22, 2018, now abandoned,which a Continuation of U.S. application Ser. No. 15/652,895, filed onJul. 18, 2017, now U.S. Pat. No. 10,624,993, which is a Continuation ofU.S. application Ser. No. 13/875,043, filed on May 1, 2013, nowabandoned, which is a Continuation of U.S. application Ser. No.11/182,551, filed on Jul. 15, 2005, now U.S. Pat. No. 8,568,761.

FIELD OF THE INVENTION

The invention relates to tissue engineering generally, and morespecifically to compositions and methods for regenerating defective orabsent mammalian tissue; particularly, myocardium tissue.

BACKGROUND OF THE INVENTION

Heart failure occurs in nearly 5 million people a year in the U.S. aloneat a combined cost of about $40 billion annually for hospitalization andtreatment of these patients. The results of all the effort and cost aredisappointing with a 75% five-year mortality rate for the heart failurevictims. Treatments for chronic heart failure include medical managementwith pharmaceutical drugs, diet and exercise, transplantation for a fewlucky recipients, and mechanical assist devices, which are costly andrisk failure and infection. Thus, the landscape for cardiac treatment isturning in recent years to transplantation of tissue or cells.

Medical researchers have transplanted human hematopoietic stem cells,mesenchymal stem cells, endothelial precursor cells, cardiac stem cells,and skeletal myoblasts or bone marrow cells to the myocardium, withhowever little or mixed success in satisfactory regeneration of themyocardium. Another protocol involved injecting transforming growthfactor beta preprogrammed bone marrow stem cells to the myocardium, withgreater success than transplantation of bone marrow stem cells alone,but without generation of contractile myocardium.

After myocardial infarction, injured cardiomyocytes are replaced byfibrotic tissue promoting the development of heart failure. On the basisthat embryonic stem cells may be directed to differentiate into truecardiomyocytes, transplantation of embryonic stem cells to a site ofmyocardial infarction may yield success in myocardial tissueregeneration, though the experiments have not yet so proven. For arelated challenge, to induce angiogenesis in ischemic myocardial tissue,transplanting endothelial progenitor cells, with or without angiogenicprotein factors has been proposed to generate capillary blood vessels atthe site of ischemia in the myocardium. As yet, the experiments to provethese theories have not worked sufficiently to be attempted in humans.

Meanwhile, typical structural abnormalities or damage to the heart thatwould lend itself to tissue regenerative therapies, were they available,include atrial septal defects, ventricular septal defects, rightventricular out flow stenosis, ventricular aneurysms, ventricularinfarcts, ischemia in the myocardium, infarcted myocardium, conductiondefects, conditions of aneurysmal myocardium, ruptured myocardium, andcongenitally defective myocardium, and these defective conditions remainuntreated in humans by any current tissue regenerative techniques.

Although tissue regeneration has been accomplished by transplantation inmammalian tissues such as the endocranium, the esophagus, blood vessels,lower urinary tract structures, and musculotendinous tissues, hearttissue regeneration by foreign tissue explant has remained a challenge.Recently, myocardium has been regenerated using xenogeneic extracellularmatrix patches in pigs and dogs, and the contractility achieved was at90% of normal.

It would be beneficial for treatment of heart failure in humans todevelop myocardium regenerative strategies using matrices and additivesfor optimizing the potential results. One problem exists in thepreparation of extracellular scaffolds in that they must benon-immunogenic and thus acellular before implantation. Getting rid ofthe cells in the matrix may also inadvertently strip the scaffold of keybioactive proteins. In order to perform procedures to regenerate humanmyocardium with fidelity, compositions that mimic the function ofextracellular matrices are provided below.

No experimentation has been conducted to date on regenerating mammalianmyocardium using an emulsified or injectable extracellular matrixformulation. The only known experimental use of extracellular emulsionsfor tissue regeneration have been with gastroesophageal repair toprevent reflux and urinary bladder sphincter repair. Both of theseexperiments were conducted in non-human animals. Some veterinary use ofextracellular matrix emulsions has been reported, but none of those useswere for the repair of myocardium. The disadvantage of using intact,non-emulsified extracellular matrix compositions such as patches orstrips is that placement of the material requires open surgery, with itscoordinate risk of infection, challenge of access to the site, andlonger recovery for the patient post-procedure.

The present invention pioneers compositions and alternatives to priorart solutions for tissue regeneration to provide a biomedicalcomposition (and methods using the composition) for regeneratingdefective or absent myocardium, particularly for use in humans.

SUMMARY OF THE INVENTION

An object of the invention is to provide sheet structures forregenerating damaged or diseased mammalian tissue.

In a preferred embodiment, the sheet structures comprise acellulardermal mammalian tissue comprising extracellular matrix (ECM) and asupplemental bioactive agent or component.

In some embodiments, the supplemental bioactive component comprises anexogenously added cell such as, without limitation, an embryonic stemcell, a mesenchymal stem cell and a hematopoietic stem cell.

In some embodiments, the supplemental bioactive component comprises anexogenously added nucleic acid such as, without limitation, DNA and RNA.

In some embodiments, the RNA comprises mRNA, tRNA, rRNA or a syntheticRNA.

In some embodiments of the invention, the damaged or diseased mammaliantissue comprises cardiovascular tissue, e.g., myocardium tissue.

Another object of the invention is to provide a method for treatingdamaged or diseased mammalian tissue that includes the steps ofproviding an acellular dermal tissue sheet structure of the inventionand disposing the sheet structure proximate the damaged or diseasedmammalian tissue, wherein the sheet structure induces remodeling of thedamaged or diseased tissue and regeneration of new tissue.

In some embodiments of the invention, the damaged or diseased mammaliantissue similarly comprises cardiovascular tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts cell-ECM interaction through the matrix proteoglycans,glycosaminoglycans and growth factors.

FIG. 2 depicts cell-cell adhesions, and cell-matrix adhesions throughspecific structural and functional molecules of the ECM.

FIG. 3 depicts a model of matrix scaffold structure including commoncollagen, proteoglycans, and glycoproteins.

DETAILED DESCRIPTION OF THE INVENTION

The invention is a composition that regenerates defective or absentmyocardium and restores cardiac function. For this purpose, anemulsified or injectable extracellular matrix composition can be derivedfrom a mammalian or synthetic source. The composition can furtherinclude added cells or protein or both. An extracellular matrixcomposition of any formulation can also include an additional componentsuch as: a) a cell, b) a peptide, polypeptide, or protein, or c) avector expressing a DNA of a bioactive molecule, and d) other additiveslike nutrients or drug molecules. One additional component can be usedin the composition or several. The composition can be placed in contactwith the defective or absent myocardium, resulting in myocardial tissueregeneration and restoration of contractility, conductivity, or functionto the heart muscle. The invention appreciates the importance of thepresence of some amount and form of an extracellular matrix, orextracellular matrix-like scaffold, as a framework for the essentialactivities of cell-cell, matrix-cell, protein-cell, and protein-proteininteractions that form the dynamic tissue regenerative process in vivo,potentially optimized by the presence of added cells, proteins, or otherbioactive components.

A composition to accomplish regeneration of myocardium needs to inducecomplex dynamic interactions and activities at the site of defect. Thepresent invention provides a composition that creates an environment invivo to allow these processes to occur. The processes needed toregenerate myocardium include specific phenotypic changes in stem cellsthat are recruited to the defective site, establishment of cell-cellconnections, establishment of vascular supply at the site, beginning ofnormal tissue specific metabolism, limiting new growth once new tissueis made, coupling electric conduction from new cells to existing cellsand pathways, and establishment of cell-extracellular matrix connectionsby way of cell adhesions to the matrix proteins.

The expectations for the extracellular matrix scaffold are that it willorganize the cells into tissues, both by recruiting endogenous cells andusing cells that have been provided as additional components in thecomposition. The extracellular matrix scaffold then coordinates thefunction of the newly recruited or added cells, allowing also for cellmigration within the matrix. The matrix allows and provides for normalmetabolism to the cells once the vascular supply delivering nutrients tothe cells is established. Additionally, signal transduction pathways forgrowth, differentiation, proliferation and gene expression areestablished.

The extracellular matrix of myocardium is complex. There is athree-dimensional architecture established with proteoglycan molecules,with available cytokines in the microenvironment. Cell movement occursusing focal adhesions, and eventually permanent cell adhesions occurcalled hemidesmosomes. Environmental signals are transmitted, includingspecific cell signals from growth factors on cell surfaces and disposedwithin the matrix framework as well. The matrix itself has structuralcomponents and functional components and the line between the twosometimes blurs because some of the moieties of structural componentssignal and trigger protein activation, and activation of nearby cells.See FIG. 1 for an illustration of, signaling, FIG. 2 for depiction ofcell-cell, protein-cell, and matrix-cell interactions, and FIG. 3 for adiagrammatic view of three-dimensional ECM scaffold.

There has been much research recently to elucidate the properties andfunction of the extracellular matrix: its protein make-up, and its rolein the body. The extracellular matrix (ECM) is a scaffold matrix ofpolymerized “structural” proteins that fit into three groups: collagens,glycoproteins, and proteoglycans (which have glycosaminoglycan repeatsthroughout). These molecules actually polymerize to form the scaffold ormatrix of proteins that exists in dynamic interaction with cells, andclosely placed functional proteins (either on the cells or bound to astructural protein).

Thus, the extracellular matrix also includes within its matrix scaffold“functional” proteins that interact with the structural proteins andwith migrating or recruited cells, particularly stem cells in tissueregeneration. The matrix functional proteins also interact with proteinexpressing cells during the life and maintenance of the matrix scaffolditself as it rebuilds and maintains its components. Note that someproteins fall into both a structural protein classification and afunctional protein classification, depending on the protein'sconfiguration and placement in the whole matrix.

The extracellular matrix of myocardium is made up of collagen types I(which is predominant), III, IV, V, and VI, combined which are 92% ofthe dry weight of the matrix. Glycosaminoglycans (GAGs) includechondroitin sulfate A and B, heparan, heparin, and hyaluronic acid.Glycoproteins such as fibronectin and entactin, proteoglycans such asdecorin and pedecan, and growth factors such, as transforming growthfactor beta (TGF-beta), fibroblast growth factor-2 (FGF-2) and vascularendothelial growth factor (VEGF), are key players in the activity of amyocardium regenerating matrix. Furthermore, the precise chemicalconstitution of the matrix appears to play a role in its function,including for example what collagen type is prevalent in the matrix, thepore size established by the matrix scaffold, the forces transmitted toadhesion molecules and mechanoreceptors in the cell membranes of cellsat the matrix, and the forces directed from the three-dimensionalenvironment (for example the gene expression in the three-dimensionalmatrix scaffold environment is very different than in a monolayerenvironment). Thus, the outcome of any tissue regenerative processes isdetermined by the structural and functional components of the matrixscaffold that form the basis of the regenerative process.

More specifically, when in early regenerative processes, circulatingcells or added cells are directed, initial temporary cell adhesionprocesses occur that result in embryogenesis of the cells, morphogenesisof the cells, regeneration of cell form, eventual maintenance of thecell, possible motility to another site, and organogenesis that furtherdifferentiates the cell. Facilitating these early cell adhesionfunctions are cell adhesion molecules (CAMs). The CAMs are availableeither endogenously or added as an additional component of thecomposition. CAMs are glycoproteins lodged in the surface of the cellmembrane or transmembrane connected to cytoskeletal components of thecell. Specific CAMs include cadherins that are calcium dependent, andmore than 30 types are known.

Also working as CAMs are integrins, which are proteins that link thecytoskeleton of the cell in which they are lodged to the extracellularmatrix or to other cells through alpha and beta transmembrane subunitson the integrin protein. See FIG. 2 for an illustration of theseinteractions. Cell migration, embryogenesis, hemostasis, and woundhealing are so facilitated by the integrins in the matrix. Syndecans areproteoglycans that combine with ligands for initiating cell motility anddifferentiation. Immunoglobins provide any necessary immune andinflammatory responses. Selectins promote cell-cell interactions.

Specific requirements for the scaffold component of the invention,whether a native scaffold prepared for introduction into a mammal, or asynthetic scaffold formed by synthetic polymerizing molecules, or acombination of the two, are that the scaffold must be resorbable overtime as the tissue regeneration ensues, and this resorption is at anappropriate degradation rate for optimal tissue regeneration and absenceof scar tissue formation.

The extracellular matrix scaffold is preferably non-toxic and provides athree-dimensional construction at the site of defect in the myocardium(once delivered to the site). The matrix scaffold is required to have ahigh surface area so that there is plenty of room for the biologicalactivities required of the tissue regeneration process. The scaffoldmust be able to provide cellular signals such as those mentioned hereinthat facilitate tissue regeneration. Finally, the scaffold needs to benon-immunogenic so that it is not rejected by the host, and it needs tobe non-thrombogenic.

Particular study of the components of the native scaffolds facilitatesdesign of compositions well-suited for regeneration of myocardium.

Collagens, the most abundant components of ECM, are homo- orheterotrimeric molecules whose subunits, the alpha chains, are distinctgene products. To date 34 different alpha chains have been identified.The sequence of the alpha chains contains a variable number of classicalGly-X-Y repetitive motifs which form the collagenous domains andnon-collagenous domains. The collagenous portions of 3 homologous orheterologous alpha chains are folded together into a helix with a coiledcoil conformation that constitutes the basic structure motif ofcollagens.

Characteristically, collagens form highly organized polymers. Two mainclasses of molecules are formed by collagen polymers: the fibril-formingcollagens (collagens type I, II, III, V, and XI) and the non-fibrillarcollagens that are a more heterogeneous class. Fibril collagen moleculesusually have a single collagenous domain repeated the entire length ofthe molecule, and non-fibrillar collagen molecules have a mixture ofcollagenous and non-collagenous domains. On this basis several moresubgroups of the collagen family are identified: e.g., the basementmembrane collagens (IV, VIII, and X). In addition, most all thedifferent types of collagen have a specific distribution. For example,fibril forming collagens are expressed in the interstitial connectivetissue. The most abundant component of basement membranes is collagenIV. The multiplexins, collagens XV and XVIII are also localized to thebasement membranes.

In the extracellular matrix of the heart, collagen types I and IIIpredominate, together forming fibrils and providing most of theconnective material for typing together myocytes and other structures inthe myocardium, and thus these molecule types are involved in thetransmission of developed mechanical force in the heart. Only collagentypes I, II, III, V, and XI self-assemble into fibrils, characterized bya triple helix in the collagen molecules. Some collagens form networks,as with the basement membrane, formed by collagen IV. Type III collagendominates in the wall of blood vessels and hollow intestinal organs andcopolymerizes with type I collagen.

Proteoglycans are grouped into several families, and all have a proteincore rich in glycosaminoglycans. They control proliferation,difierentiation, and motility. The lecticans interact with hyaluronanand include aggrecan, versican, neurocan, and brevican. Versicanstimulates proliferation of fibroblasts and chondrocytes through thepresence in the molecule of EGF-like motifs. The second type ofproteoglycans have a protein core with leucine-rich repeats, which forma horse shaped protein good for protein-protein interactions. Theirglycosaminoglycan side chains are mostly chondroitin/dermatan sulphateor keratin sulphate. Decorin, biglycan, fibromodulin, and keratocan aremembers of this family. Decorin is involved in modulation anddifferentiation of epithelial and endothelial cells. In addition,transforming growth factor beta (TGF beta) interacts with members ofthis family.

There are part-time proteoglycans, comprising CD44 (a receptor forhyaluronic acid), macrophage colony stimulating factor, amyloidprecursor protein and several collagens (IX, XII, XIV, and XVIII).

The last family of proteoglycans is the heparan sulfate proteoglycans,some of which are located in the matrix, and some of which are on cellmembranes. Perlecan and agrin are matrix heparan sulfate proteoglycansfound in basement membranes. The syndecans and glypicans aremembrane-associated heparan sulfate proteoglycans, Syndecans have aheparan sulfate extracellular moiety that binds with high affinitycytokines and growth factors, including fibroblast growth factor (FGF),hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF),heparin-binding epidermal growth factor (HB-EGF), and vascularendothelial growth factor (VEGF). The heparan sulfate proteoglycans havebeen implicated in modulation of cell migration, proliferation anddifferentiation in wound healing.

Glycoproteins are also structural proteins of ECM scaffold. Theglycoprotein fibronectin (Fn) is a large dimer that attracts stem cells,fibroblasts and endothelial cells to a site of newly forming matrix.Tenascin is a glycoprotein that has Fn repeats and appears during earlyembryogenesis then is switched off in mature tissue. Tenascin reappearsduring wound healing. Other glycoprotein components of ECM includeelastin that forms the elastic fibers and is a major structuralcomponent along with collagen; fibrillins which are a family of proteinsconsisting almost entirely of endothelial growth factor (EGF)-likedomains. Small glycoproteins present in ECM include nidogententactin andfibulins I and II.

The glycoprotein laminin is a large protein with three distinctpolypeptide chains. Together with type IV collagen, nidogen, andperlecan, laminin is one of the main components of the basementmembrane. Laminin isoforms are synthesized by a wide variety of cells ina tissue-specific manner. Laminin I contains multiple binding sites tocellular proteins. Virtually all epithelial cells synthesize laminin, asdo small, skeletal, and cardiac muscle, nerves, endothelial cells, bonemarrow cells, and neuroretina. Laminins affect nearby cells, bypromoting adhesion, cell migration, and cell differentiation. They exerttheir effects mostly through binding to integrins on cell surfaces.Laminins 5 and 10 occur predominantly in the vascular basement membraneand mediate adhesion of platelets, leukocytes, and endothelial cells.

In addition to the structural matrix proteins just discussed, specificinteractions between cells and the ECM are mediated by functionalproteins of the ECM, including transmembrane molecules, mainlyintegrins, some members of the collagen family, some proteoglycans,glycosaminoglycan chains, and some cell-surface associated proteins.These interactions lead to direct or indirect control of cellularactivities within the extracellular matrix scaffold such as adhesion,migration, differentiation, proliferation, and apoptosis.

Glycosaminoglycans (GAGs) are glycosylated post-translational moleculesderived from proteoglycans. Well known. GAGs include heparin, hyaluronicacid, heparan sulfate, and chondroitin sulfate A, B, and C. Heparinchains stimulate angiogenesis, and act as subunits in a proteoglycan tostimulate the angiogenic effects of fibroblast growth factor-2 (FGF-2)(also known as basic FGF or bFGF). Chondroitin sulfate B (dermatansulfate) interacts with TGF-beta to control matrix formation andremodeling. The proteoglycan form of chondroitin sulfate B regulates thestructure of ECM by controlling collagen fibril size, orientation anddeposition. Hyaluronic acid is associated with rapid wound healing andorganized deposit of collagen molecules in the matrix. It is believedthat hyaluronic acid binds TGF-beta1 to inhibit scar formation.

The ECM is also being remodeled constantly in the live animal. Theproteins of the ECM are broken down by matrix metalloproteases, and newprotein is made and deposited as replacement protein. Collagens aremostly synthesized by the cells comprising the ECM: fibroblasts,myofibroblasts, osteoblasts, and chondrocytes. Some collagens are alsosynthesized by adjacent parenchymal cells or also covering cells such asepithelial, endothelial, or mesothelial cells.

The extracellular part of integrins bind fibronectin, collagen andlaminin, and act primarily as adhesion molecules. Integrin-ligandbinding also triggers cascades of activity for cell survival, cellproliferation, cell motility, and gene transcription.

Tenascins include cytotactin (TN-C). Cell surface receptors fortenascins include integrins, cell adhesion molecules of the Igsuperfamily, a transmembrane chondroitin sulfate proteoglycan(phosphacan) and annexin II. TN-C also interacts with extracellularproteins such as fibronectin and the lecticans (the class ofextracellular chondroitin sulphate proteoglycans including aggrecan,versican, and brevican).

In addition to direct knowledge of protein cell interaction many of theproteins associated with the ECM can initiate binding to proteins thatthen activate to bind other proteins or cells, e.g., decorin binds Fn orthrombospondin and causes their cell adhesion promoting activity. Otherproteoglycans control the hydration of the ECM and the spacing betweenthe collagen fibrils and network, which is believed to facilitate cellmigration. Proteoglycans regulate cell function by controlling growthfactor activity, e.g., decorin, biglycan, and fibromodulin bind toisoforms of transforming growth factor beta (TGF beta) and heparinsulfate proteoglycans bind and store fibroblast growth factor.

The matrix metalloproteases (MMPs) break down the collagen molecules inthe ECM so that new collagen can be used to remodel and renew the ECMscaffold. It is also believed that the proteolytic activity of MMPsaugment the bioavailability of growth factors sequestered within theECM, and can activate latent secreted growth factors like TGF-beta andIGF from IGFBPs and cell surface growth factor precursors. MMPs canproteolytically cleave cell surface growth factors, cytokines, chemokinereceptors and adhesion receptors, and thus participate in controllingresponses to growth factors, cytokines, chemokines, as well as cell-celland cell-ECM interactions.

Structural or functional matrix proteins that can comprise thecompositions herein disclosed to facilitate myocardial tissueregeneration include, minimally, collagen I and III, elastin, laminin,CD44, hyaluronan, syndecan, bFGF, HGF, PDGF, VEGF, Fn, tenascin,heparin, heparan sulfate, chondroitin sulfate B, integrins, decorin, andTGF-beta.

Native extracellular matrix scaffolds, and the proteins that form them,are found in their natural environment, the extracellular matrices ofmammals. These materials are prepared for use in mammals in tissuegratis procedures. Small intestine submucosa (SIS) is described in U.S.Pat. No. 5,275,826, urinary bladder submucosa (UBS) is described in U.S.Pat. No. 5,554,389, stomach submucosa (SS) is described in U.S. Pat. No.6,099,567, and liver submucosa (LS) or liver basement membrane (LBM) isdescribed in U.S. Pat. No. 6,379,710, to name some of the extracellularmatrix scaffolds presently available for explaining procedures. Inaddition, collagen from mammalian sources can be retrieved from matrixcontaining tissues and used to form a matrix composition. Extracellularmatrices can be synthesized from cell cultures as in the productmanufactured by Matrigel™.

In addition, dermal extracellular matrix material, subcutaneousextracellular matrix material, large intestine extracellular matrixmaterial, placental extracellular matrix material, omentum extracellularmatrix material, heart extracellular matrix material, and lungextracellular matrix material, may be used, derived and preservedsimilarly as described herein for the SIS, SS, LBM, and UBM materials.Other organ tissue sources of basement membrane for use in accordancewith this invention include spleen, lymph nodes, salivary glands,prostate, pancreas and other secreting glands. In general, any tissue ofa mammal that has an extracellular matrix can be used for developing anextracellular matrix component of the invention.

When using collagen-based synthetic ECMs, the collagenous matrix can beselected from a variety of commercially available collagen matrices orcan be prepared from a wide variety of natural sources of collagen.Collagenous matrix for use in accordance with the present inventioncomprises highly conserved collagens, glycoproteins, proteoglycans, andglycosaminoglycans in their natural configuration and naturalconcentration. Collagens can be from animal sources, from plant sources,or from synthetic sources, all of which are available and standard inthe art.

The proportion of scaffold material in the composition when native scatold used will be large, as the natural balance of extracellular matrixproteins in the native scaffolds usually represents greater than 90% ofthe extracellular matrix material by dry weight. Accordingly, for afunctional tissue regenerative product, the scaffold component of thecomposition by weight will be generally greater than 50% of the totaldry weight of the composition. Most typically, the scaffold willcomprise an amount of the composition by weight greater than 60%,greater than 70%, greater than 80%, greater than 82%, greater than 84%,greater than 86%, greater than 88%, greater than 90%, greater than 92%,greater than 94%, greater than 96%, and greater than 98% of the totalcomposition.

Native extracellular matrices are prepared with care that theirbioactivity for myocardial tissue regeneration is preserved to thegreatest extent possible. Key functions that may need to be preservedinclude control or initiation of cell adhesion, cell migration, celldifferentiation, cell proliferation, cell death (apoptosis), stimulationof angiogenesis, proteolytic activity, enzymatic activity, cellmotility, protein and cell modulation, activation of transcriptionalevents, provision for translation events, inhibition of somebioactivities, for example inhibition of coagulation, stem cellattraction, and chemotaxis. Assays for determining these activities arestandard in the art. For example, material analysis can be used toidentify the molecules present in the material composition. Also, invitro cell adhesion tests can be conducted to make sure that the fabricor composition is capable of cell adhesion.

The matrices are generally decellularized in order to render themnon-immunogenic. A critical aspect of the decellularization process isthat the process be completed with some of the key protein functionretained, either by replacement of proteins incidentally extracted withthe cells, or by adding exogenous cells to the matrix composition aftercell extraction, which cells produce or carry proteins needed for thefunction of tissue regeneration in vivo.

Myocardial tissue has been regenerated in vivo in non-humans usingnative xenogeneic extracellular matrix scaffolds in the form of intactpatches derived and prepared from mammals, so it can be presumed that atleast some of the components required for myocardial tissue regenerationare to be found in these xenogeneic patch matrices. Prudent practice maydictate that the cell extract from the patches be tested for its proteinmake-up, so that if necessary proteins are removed they can be placeback into the matrix composition, perhaps using exogenous proteins atapproximately the same amount as those detected in the extractionsolution. Replacing lost essential proteins may also be necessary withemulsions or injectable solutions of extracellular matrix, particularlythose emulsified from mammalian sources. Another option would be thatthe proteins extracted during the cell extraction process can simply beadded back after the cell extraction is complete, thus preserving thedesired bioactivity in the material.

The bioactivity of extracellular matrix material can be mimicked intissue regeneration experiments with combinations of native andsynthetic extracellular matrices explanted together, also optionallywith additional components such as proteins or cells, in order toprovide an optimal myocardial tissue regenerative composition andenvironment in vivo. What works as the best composition for myocardialtissue regeneration in patients, particularly humans can be tested firstin other mammals by standard explanting procedures to determine whethertissue regeneration is accomplished and optimized by a particularcomposition. See Badylak, et al, The Heart Surgery Forum, ExtracellularMatrix for Myocardial Repair, vol. 6(2), pp. 20-26 (2003).

When adding proteins to the extracellular matrix composition, be it anemulsified composition, or another formulation of matrix, the proteinsmay be simply added with the composition, or each protein may becovalently linked to a molecule in the matrix. Standard protein-moleculelinking procedures may be used to accomplish the covalent attachment.

For decellularization when starting with a whole organ, whole organperfusion process can be used. The organ is perfused with adecellularization agent, for example 0.1% peracetic acid rendering theorgan acellular. The organ can then be cut into portions and stored(e.g., in aqueous environment, liquid nitrogen, cold, freeze-dried, orvacuum-pressed) for later use. Any appropriate decellularizing agent maybe used in whole organ perfusion process.

With regards to submucosal tissue, extractions may be carried out a nearneutral pH (in a range from about pH 5.5 to about pH 7.5) in order topreserve the presence of growth factor in the matrices. Alternatively,acidic conditions (i.e., less than 5.5 pH) can be used to preserve thepresence of glycosaminoglycan components, at a temperature in a rangebetween 0 and 50 degrees centigrade. In order to regulate the acidic orbasic environment for these aqueous extractions, a buffer and chaotropicagent (generally at a concentration from about 2M to about 8M) areselected, such as urea (at a concentration from about 2M to 4M),guanidine (at a concentration from about 2M to about 6M, most typicallyabout 4M), sodium chloride, magnesium chloride, and non-ionic or ionicsurfactants. Urea at 2M in pH 7.4 provides extraction of basis FGF andthe glycoprotein fibronectin. Using 4M guanidine with pH 7.4 bufferyields a fraction having transforming growth factor beta (TGF-beta).Accordingly, it may behoove a practitioner to decellularize one portionof a matrix, and extract desired proteins to add back in from otherdifferent portions.

Because of the collagenous structure of basement membrane and the desireto minimize degradation of the membrane structure during celldissociation, collagen specific enzyme activity should be minimized inthe enzyme solutions used in the cell-dissociation step. For example,liver tissue is typically also treated with a calcium chelating agent orchaotropic agent such as a mild detergent such as Triton 100. The celldissociation step can also be conducted using a calcium chelating agentor chaotropic agent in the absence of an enzymatic treatment of thetissue. The cell-dissociation step can be carried out by suspendingliver tissue slices in an agitated solution containing about 0.05 toabout 2%, more typically about 0.1 to about 1% by weight protease,optionally containing a chaotropic agent or a calcium chelating agent inan amount effective to optimize release and separation of cells from thebasement membrane without substantial degradation of the membranematrix.

After contacting the liver tissue with the cell-dissociation solutionfor a time sufficient to release all cells from the matrix, theresulting liver basement membrane is rinsed one or more times withsaline and optionally stored in a frozen hydrated state or a partiallydehydrated state until used as described below. The cell-dissociationstep may require several treatments with the cell-dissociation solutionto release substantially all cells from the basement membrane. The livertissue can be treated with a protease solution to remove the componentcells, and the resulting extracellular matrix material is furthertreated to remove or inhibit any residual enzyme activity. For example,the resulting basement membrane can be heated or treated with one ormore protease inhibitors.

Basement membrane or other native ECM scaffolds may be sterilized usingconventional sterilization techniques including tanning withglutaraldehyde, formaldehyde tanning at acidic pH, ethylene oxidetreatment, propylene oxide treatment, gas plasma sterilization, gammaradiation, and peracetic acid sterilization. A sterilization techniquewhich does not significantly weaken the mechanical strength andbiotropic properties of the material is preferably used. For instance,it is believed that strong gamma radiation may cause loss of strength inthe graft material. Preferred sterilization techniques include exposingthe graft to peracetic acid, low dose gamma irradiation and gas plasmasterilization; peracetic acid sterilization being the most preferredmethod.

Synthetic extracellular matrices can be formed using synthetic moleculesthat polymerize much like native collagen and which form a scaffoldenvironment that mimics the native environment of mammalianextracellular matrix scaffolds. According, such materials aspolyethylene terephthalate fiber (Dacron), polytetrafluoroethylene(PTFE), glutaraldehyde-cross linked pericardium, polylactate (PLA),polyglycol (PGA), hyaluronic acid, polyethylene glycol (PEG),polyethylene, nitinol, and collagen from non-animal sources (such asplants or synthetic collagens), can be used as components of a syntheticextracellular matrix scaffold. The synthetic materials listed arestandard in the art, and forming hydrogels and matrix-like materialswith them is also standard. Their effectiveness can be tested in vivo assited earlier, by testing in mammals, along with components thattypically constitute native ECMs, particularly the growth factors andcells responsive to them.

The ECM-like materials are described generally in the review article“From Cell-ECM Interactions to Tissue Engineering”, Rosso, et al.,Journal of Cellular Physiology 199:174-180 (2004). In addition, someECM-like materials are listed here. Particularly useful biodegradableand/or bioabsorbable polymers include polylactides, poly-glycolides,polycaprolactone, polydioxane and their random and block copolymers.Examples of specific polymers include poly D,L-lactide,polylactide-co-glycolide (85:15) and polylactide-co-glycolide (75:25).

Preferably, the biodegradable and/or bioabsorbable polymers used in thefibrous matrix of the present invention will have a molecular weight inthe range of about 1,000 to about 8,000,000 g/mole, more preferablyabout 4,000 to about 250,000 g/mole. The biodegradable and/orbioabsorbable fiberizable material is preferably a biodegradable andbioabsorbable polymer. Examples of suitable polymers can be found inBezwada, et al. (1997) Poly(p-Dioxanone) and its copolymers, in Handbookof Biodegradable Polymers, A. J. Domb, J. Kost and D. M. Wiseman,editors, Hardwood Academic Publishers, The Netherlands, pp. 29-61.

The biodegradable and/or bioabsorbable polymer can contain a monomerselected from the group consisting of a glycolide, lactide, dioxanone,caprolactone, trimethylene carbonate, ethylene glycol and lysine. Thematerial can be a random copolymer, block copolymer or blend ofmonomers, homopolymers, copolymers, and/or heteropolymers that containthese monomers.

The biodegradable and/or bioabsorbable polymers can containbioabsorbable and biodegradable linear aliphatic polyesters such aspolyglycolide (PGA) and its random copolymer poly(glycolide-co-lactide-)(PGA-co-PLA). The FDA has approved these polymers for use in surgicalapplications, including medical sutures. An advantage of these syntheticabsorbable materials is their degradability by simple hydrolysis of theester backbone in aqueous environments, such as body fluids. Thedegradation products are ultimately metabolized to carbon dioxide andwater or can be excreted via the kidney. These polymers are verydifferent from cellulose-based materials, which cannot be absorbed bythe body.

Other examples of suitable biocompatible polymers are polyhydroxyalkylmethacrylates including ethylmethacrylate, and hydrogels such aspolyvinylpyrrolidone, polyacrylamides, etc. Other suitable bioabsorbablematerials are biopolymers which include collagen, gelatin, alginic acid,chitin, chitosan, fibrin, hyaluronic acid, dextran, polyamine acids,polylysine and copolymers of these materials. Any glycosaminoglycan(GAG) type polymer can be used. GAGs can include, e.g., heparin,chondroitin sulfate A or B, and hyaluronic acid, or their syntheticanalogues. Any combination, copolymer, polymer or blend thereof of theabove examples is contemplated for use according to the presentinvention. Such bioabsorbable materials may be prepared by knownmethods.

Nucleic acids from any source can be used as a polymeric biomaterial.Sources include naturally occurring nucleic acids as well as synthesizednucleic acids. Nucleic acids suitable for use in the present inventioninclude naturally occurring forms of nucleic acids, such as DNA(including the A, B and Z structures), RNA (including mRNA, tRNA, andrRNA together or separated) and cDNA, as well as any synthetic orartificial forms of polynucleotides.

The nucleic acids used in the present invention may be modified in avariety of ways, including by cross linking, intra-chain modificationssuch as methylation and capping, and by copolymerization. Additionally,other beneficial molecules may be attached to the nucleic acid chains.The nucleic acids may have naturally occurring sequences or artificialsequences. The sequence of the nucleic acid may be irrelevant for manyaspects of the present invention. However, special sequences may be usedto prevent any significant effects due to the information codingproperties of nucleic acids, to elicit particular cellular responses orto govern the physical structure of the molecule.

Nucleic acids may be used in a variety of crystalline structures both infinished biomaterials and during their production processes. Nucleicacid crystalline structure may be influenced by salts used with thenucleic acid. For example, Na, K, Bi and Ca salts of DNA all havedifferent precipitation rates and different crystalline structures.Additionally, pH influences crystalline structure of nucleic acids.

The physical properties of the nucleic acids may also be influenced bythe presence of other physical characteristics. For instance, inclusionof hairpin loops may result in more elastic biomaterials or may providespecific cleavage sites. The nucleic acid polymers and copolymersproduced may be used for a variety of tissue engineering applicationsincluding to increase tissue tensile strength, improve wound healing,speed up wound healing, as templates for tissue formation, to guidetissue formation, to stimulate nerve growth, to improve vascularizationin tissues, as a biodegradable adhesive, as device or implant coating,or to improve the function of a tissue or body part. The polymers mayalso more specifically be used as sutures, scaffolds and wounddressings. The type of nucleic acid polymer or copolymer used may affectthe resulting chemical and physical structure of the polymericbiomaterial.

The extracellular matrix can be emulsified for administration to thedefective or absent myocardium. The matrix may also be otherwiseliquefied or made into an injectable solution, such as an emulsion, or aliquid, or injectable gel, or semi-gel, other injectable formulationthat can be administered with a percutaneous catheter, or other devicecapable of delivering an injectable formulation.

An emulsion of mammalian or synthetic extracellular matrix material canbe accomplished as is standard for tissue or polymer emulsification ingeneral. Generally, the emulsion will be maintained in an emulsifiedstate by control of some component of the composition, for example thepH. Upon delivery of the emulsion the pH is altered to allow themolecules of the matrix to polymerize into a three-dimensional scaffold.

An emulsified extracellular matrix material comprising also cells canhave the cultured cells simply added into the matrix emulsion, or thecells may be co-cultured with the matrix for a time beforeadministration to the patient. Standard procedures for culturing orco-culturing cells can be used. In addition, where proteins such asgrowth factors, or any other protein, including protein forms such aspeptides or polypeptides, or protein fragments, are added into theextracellular matrix, the protein molecules may be added into the matrixcomposition, or the protein molecules may be covalently linked to amolecule in the matrix. The covalent linking of protein to matrixmolecules can be accomplished by standard covalent protein linkingprocedures known in the art. The protein may be covalently linked to oneor more matrix molecules. The covalent linking may result in anintegration of the protein molecules in the matrix scaffold formationonce the emulsion converts from the emulsified form to the scaffold formof the extracellular matrix.

Unlike skeletal myocytes, cardiomyocytes withdraw from cell cycleshortly after birth, and adult mammalian cardiomyocytes lack thepotential to proliferate. Therefore, in order to regenerate myocardium,the right cells may have to be added to the composition, or the site, orthe right molecules to attract the right cells will have to be added tothe composition or the site. Transplantation cell sources for themyocardium include allogenic, xenogeneic, or autogenic sources.Accordingly, human embryonic stem cells, neonatal cardiomyocytes,myofibroblasts, mesenchymal cells, autotransplanted expandedcardiomyocytes, and adipocytes can be used as additive components toaccompany the scaffold.

Embryonic stem cells begin as totipotent cells, differentiate topluripotent cells, and then further specialization. They are cultured exvivo and in the culture dish environment differentiate either directlyto heart muscle cells, or to bone marrow cells that can become heartmuscle cells. The cultured cells are then transplanted into the mammal,either with the composition or in contact with the scaffold and othercomponents.

Myoblasts are another type of cell, that lend themselves totransplantation into myocardium, however, they do not always developinto cardiomyocytes in vivo. Adult stem cells are yet another species ofcell that work in the context of tissue regeneration. Adult stem cellsare thought to work by generating other stem cells (for example thoseappropriate to myocardium) in a new site, or they differentiate directlyto a cardiomyocyte in vivo. They may also differentiate into otherlineages after introduction to organs, such as the heart. The adultmammal provides sources for adult stem cells in circulating endothelialprecursor cells, bone marrow-derived cells, adipose tissue, or cellsfrom a specific organ. It is known that mononuclear cells isolated frombone marrow aspirate differentiate into endothelial cells in vitro andare detected in newly formed blood vessels after intramuscularinjection. Thus, use of cells from bone marrow aspirate may yieldendothelial cells in vivo as a component of the composition.

Other cells which may be employed with the invention are the mesenchymalstem cells administered with activating cytokines. Subpopulations ofmesenchymal cells have been shown to differentiate toward myogenic celllines when exposed to cytokines in vitro.

Once a type of cell is chosen, the number of cells needed is determined.Their function and anticipated change upon implantation, as well astheir viability during the process of transplantation need to beconsidered to determine the number of cells to transplant. Also the modeof transplantation is to be considered: several modes includingintracoronary, retrograde venous, transvascular injection, directplacement at the site, thoracoscopic injection and intravenous injectioncan be used to put the cells at the site or to incorporate them with thecomposition either before delivery or after delivery to the defectivemyocardium. In all cases, the mode of delivery and whether the cells arefirst mixed with the other components of the composition is a decisionmade based on what will provide the best chance for viability of thecells, and the best opportunity for their continued development intocells that can function in the scaffold in vivo in order to signal andpromote tissue regeneration.

The following list includes some of the cells that may be used asadditional cellular components of the composition of the invention: ahuman embryonic stem cell, a fetal cardiomyocyte, a myofibroblast, amesenchymal stem cell, an autotransplanted expanded cardiomyocyte, anadipocyte, a totipotent cell, a pluripotent cell, a blood stem cell, amyoblast, an adult stem cell, a bone marrow cell, a mesenchymal cell, anembryonic stem cell, a parenchymal cell, an epithelial cell, anendothelial cell, a mesothelial cell, a fibroblast, a myofibroblast, anosteoblast, a chondrocyte, an exogenous cell, an endogenous cell, a stemcell, a hematopoietic stem cell, a pluripotent stem cell, a bonemarrow-derived progenitor cell, a progenitor cell, a myocardial cell, askeletal cell, a fetal cell, an embryonic cell, an undifferentiatedcell, a multi-potent progenitor cell, a unipotent progenitor cell, amonocyte, a cardiomyocyte, a cardiac myoblast, a skeletal myoblast, amacrophage, a capillary endothelial cell, a xenogeneic cell, anallogenic cell, an adult stem cell, and a post-natal stem cell.

In particular, human embryonic stem cells, fetal cardiomyocytes,mesenchymal stem cells, adipocytes, bone marrow progenitor cells,embryonic stem cells, adult stem cells, or post-natal stem cellstogether with growth factors or alone with matrix scaffold optimizemyocardium regeneration in vivo.

Cells can be seeded directly onto matrix scaffold sheets underconditions conducive to eukaryotic cell proliferation. The highly porousnature of extracellular matrices in particular will allow diffusion ofcell nutrients throughout the membrane matrix. Thus, cells can becultured on or within the matrix scaffold itself. With the emulsifiedextracellular matrix compositions, or with some of the otherformulations, the cells can be co-cultured with the extracellular matrixmaterial before administration of the complete composition to thepatient.

In addition to a native ECM scaffold, or a synthetic scaffold, or amixture of the two, peptides, polypeptides or proteins can be added.Such components include extracellular structural and functional proteinsin admixture so as to mimic either heart ECM, or other native ECMs thatare capable of regenerating at least some reasonable percentage of thedefective myocardium, for example at least 30%, preferably more than50%. Effective regeneration of the myocardium relies on theextracellular matrix scaffold by its structure and components. Mimickingthe native explant material as closely as possible thus optimizes theopportunity for regeneration using a composition comprising some nativeECM, albeit treated, but also with additional components.

The peptides, polypeptides or proteins that can be added to the scaffoldare: a collagen, a proteoglycan, a glycosaminoglycan (GAG) chain, aglycoprotein, a growth factor, a cytokine, a cell-surface associatedprotein, a cell adhesion molecule (CAM), an angiogenic growth factor, anendothelial ligand, a matrikine, a matrix metalloproteinase, a cadherin,an immunoglobin, a fibril collagen, a non-fibrillar collagen, a basementmembrane collagen, a multiplexin, a small-leucine rich proteoglycan,decorin, biglycan, a fibromodulin, keratocan, lumican, epiphycan, aheparan sulfate proteoglycan, perlecan, agrin, testican, syndecan,glypican, serglycin, selectin, a lectican, aggrecan, versicanonterocan,brevican, cytoplasmic domain-44 (CD-44), macrophage stimulating factor,amyloid precursor protein, heparin, chondroitin sulfate B (dermatansulfate), chondroitin sulfate A, heparan sulfate, hyaluronic acid,fibronectin (Fn), tenascin, elastin, fibrillin, laminin,nidogententactin, fibulin I, fibulin II, integrin, a transmembranemolecule, platelet derived growth factor (PDGF), epidermal growth factor(EGF), transforming growth factor alpha (TGF-alpha), transforming growthfactor beta (TGF-beta), fibroblast growth factor-2 (FGF-2) (also calledbasic fibroblast growth factor (bFGF)), thrombospondin, osteopontin,angiotensin converting enzyme (ACE), and vascular endothelial growthfactor (VEGF).

Typically, the additional peptide, polypeptide, or protein componentwill comprise an amount of the composition by weight selected from thegroup consisting of greater than 0.1%, greater than 0.5%, greater than1%, greater than 1.5%, greater than 2%, greater than 4%, greater than5%, greater than 10%, greater than 12%, greater than 15%, and greaterthan 20%.

Evaluation of the effectiveness of a particular protein component orcombination of components for myocardial tissue regeneration may beaccomplished by contacting the composition with defective myocardium ina test animal, for example a dog, pig, or sheep, or other common testmammal. Myocardial tissue regeneration and myocardium contractility areboth indicia to measure the success of the composition and procedure, byprocedures standard in the art. In addition, a small sampling of theregenerated tissue can be made to determine that new extracellularmatrix and new tissue has been made. As to what balance betweenstructural extracellular matrix proteins and functional ones to use in agiven composition, nature provides direction. Most ECMs arepredominantly made up of structural proteins by dry weight. Thus only asmall portion of functional proteins by weight is needed for effectivemyocardial tissue regeneration.

Peptides, polypeptides or proteins for the composition may be formulatedas is standard in the art for the particular class of protein, and thatformulation may be added to the extracellular matrix material (ofwhatever formulation) for delivery into the patient.

Alternatively, the protein molecules may be covalently linked to anappropriate matrix molecule of any of the matrix formulations. Covalentlinking of the protein molecules to molecules of the matrix may beaccomplished by standard covalent linking methods known in the art.

Some of the proteins required for the composition can be geneticallysynthesized in viva with DNA and vector constituents. Thus, a vectorhaving a DNA capable of targeted expression of a selected gene cancontribute a bioactive peptide, polypeptide, or protein to thecomposition. Standard in viva vector gene expression can be employed.

In addition, other additives such as a nutrient, a sugar, a fat, alipid, an amino acid, a nucleic acid, a ribonucleic acid, may providesupport to the regenerative process in vivo in the composition. Finally,also a drug, such as a heart regenerating or angiogenesis promoting drugmay be also added to the composition, in such a form as, for example, anorganic molecule, an inorganic molecule, a small molecule, a drug, orany other drug-like bioactive molecule.

A formulation of extracellular matrix material can be an emulsified orinjectable material derived from mammalian or synthetic sources. Theextracellular matrix material can be emulsified or made into aninjectable formulation by standard procedures in the art, and maintainedas an emulsion or injectable until delivered to the patient. Oncedelivered to the patient, an environment is established (by some changesuch as a change in pH) so that the extracellular matrix molecules (bethey mammalian or synthetic) polymerize to form a matrix scaffold.

Depending on the nature of the scaffold selected, and depending on whichadditional components are used, the scaffold component and theadditional component can be formulated together in the same way, or indifferent ways that are however but delivery-compatible with each otherfor delivery purposes. Options for formulation of the scaffold include asolid sheet, multilaminate sheets, a gel, an emulsion, an injectablesolution, a fluid, a paste, a powder, a plug, a strand, a suture, acoil, a cylinder, a weave, a strip, a spray, a vapor, a patch, a sponge,a cream, a coating, a lyophilized material, or a vacuum pressedmaterial, all of which are standard in the art.

Formulation of the additional components, when they are notscaffold-like is generally accomplished using some form of aninjectable, semi-gel, or emulsified material, although powdered formsmay also then be combined with a hydration-promoting solution atdelivery. Thus, formulations for the additional components willgenerally comprise formulations of the nature of a gel, an emulsion, aninjectable solution, a fluid, a paste, a spray, a vapor, a cream, and acoating. Dried materials that are hydrated either at delivery or justbefore delivery are powders, such as lyophilized materials.

Cells can be added in from a culture, or can be co-cultured with thematrix component of the composition. Proteins can be added into thecomposition, or covalently linked to matrix molecules. DNA can be addedin with their vectors for expressing proteins in vivo. Other additivescan be combined with the matrix component as is practical for thedelivery of the composition (for example, as an injectable or acomposition administered with a percutaneous catheter) and as ispractical for maintaining bioactivity of the molecules or components invivo.

Fluidized forms of native extracellular matrices are described, e.g., inU.S. Pat. No. 5,275,826. The comminuted fluidized tissue can besolubilized by enzymatic digestion including the use of proteases, suchas trypsin or pepsin, or other appropriate enzymes such as a collagenaseor a glycosaminoglycanase, or the use of a mixture of enzymes, for aperiod of time sufficient to solubilize said tissue and form asubstantially homogeneous solution.

The present invention also contemplates the use of powder forms ofextracellular matrix scaffolds. In one embodiment a powder form isprepared by pulverizing basement membrane submucosa tissue under liquidnitrogen to produce particles ranging in size from 0.1 to 1 mm². Theparticulate composition is then lyophilized overnight and sterilized toform a solid substantially anhydrous particulate composite.Alternatively, a powder form of basement membrane can be formed fromfluidized basement membranes by drying the suspensions or solutions ofcomminuted basement membrane. The dehydrated forms have been rehydratedand used as cell culture substrates without any apparent loss of theirability to support cell growth.

The mode used for delivery of the compositions of the invention to thedefective myocardium may be critical in establishing tissue regenerationin vivo. Standard delivery to myocardial sites can be used forinjectable, fluidized, emulsified, gelled, or otherwise semi-fluidmaterials, such as direct injecting (e.g., with a needle and syringe),or injecting with a percutaneous catheter. For materials that have beenrendered wholly or partially vaporized, force-driven delivery of thematerial can be used, for example, CO₂ powering emission of fineemulsion, micronizing an injectable solution, ink jet delivery, spraywith a conventional atomizer or spray unit, or other type of vaporizeddelivery. Some of these vaporized formulations can be delivered using apercutaneous catheter adapted for delivery of a vaporized formulation.

For materials that are essentially solid, such as some of the native orsynthetic scaffolds, physically depositing the material will be the mostprudent mode of delivery. For example, a patch, sponge, strip, weave, orother geometrically defined material form should be placed at the siteof deposit either during surgery, or with a percutaneous minimallyinvasive catheter capable of depositing all or portions of solidmaterial at the site. Preferred modes of delivery will be minimallyinvasive delivery procedures, which reduce the risk of infection andprovide an easier recovery for the patient.

Where the scaffold component is in a different material form than theadditional components, care must be taken to orchestrate an effectivedelivery of both components to the site. For example, where the scaffoldis a solid sheet, and cells have been cultured and proteins hydrolyzed,the cells and proteins may be added to the scaffold prior to deliveryand the composition is then delivered in surgery. Alternatively, also insurgery, the solid sheet of scaffold may be delivered, and theemulsified agents deposited on the sheet before closure. Where both thescaffold component and the additional components can be emulsified, withcomplete retention of functionality, the composition can be deliveredtogether by direct injection or percutaneous catheter delivery.

In all cases, before a mode is used to treat a patient, the feasibilityand effectiveness of any one delivery mode or combination of modes canbe tested in a test mammal prior to actual use in humans.

A site of defective myocardium is identified and the appropriatecomposition of a scaffold component and additional components is madeand formulated. The formulated composition is delivered by anappropriate means to the site of defect. The site and mammal areobserved and tested for regeneration of the defective myocardium todetermine that an effective amount of the composition has beendelivered, particularly to observe new tissue growth, and also todetermine that the new tissue has the contractility necessary for it tofunction usefully as myocardium. Tissue growth and contractility can betested and observed by standard means, for example, as described inBadylak, et al. referenced above.

Goals for contractility in the defective myocardium include observed andmeasured contractility in an amount measured against contractility of anormal heart selected from the group consisting of greater than 10%,greater than 20%, greater than 30%, greater than 40%, greater than 50%,greater than 60%, greater than 70%, greater than 80%, greater than 90%,and greater than 95% of normal myocardial contractility in vivo.

The method step of contacting the defective myocardium or site of absentmyocardium with a composition of the invention can be accomplished bymeans discussed in the delivery section, including, delivering thecomposition by injecting, suturing, stapling, injecting with apercutaneous catheter, CO₂ powering emission of fine emulsion,micronizing an injectable solution, inkjet delivery, physicallydepositing a sponge, physically depositing a patch, physical depositinga strip, or physically depositing a formed scaffold of any shape.

A complementary method of use of the compositions of the inventionincludes a method of inducing angiogenesis in myocardium at a site ofischemia by similarly contacting said ischemic myocardium with acomposition of the invention in an amount effective to induceangiogenesis in the myocardium at the site of ischemia. Effectivenesscan be measured by measuring vascularization at the site, using standardbiomedical procedures for such analysis.

EXAMPLES Example 1

An emulsion of urinary bladder submucosa (UBS) is prepared using,standard emulsifying techniques. The emulsion is free of endogenouscells. This preparation is maintained as an emulsion by controlling thepH during storage of the emulsion before it is administered to thepatient. In a minimally invasive procedure, a percutaneous catheterdevice is loaded with sufficient quantity of the emulsified UBS toaddress a defect in a human heart, the defect having been identifiedpreviously by imaging. The catheter is directed to the site of themyocardium in need of tissue regeneration using sonographic orradiographic imaging. Upon contact with the site, the emulsion isreleased, and the catheter is withdrawn. The tissue regeneration processis monitored by sonography for several weeks or months post-delivery ofthe emulsion.

Example 2

An emulsion of decellularized immunogenic liver basement membrane (LBM)is prepared using standard known techniques. While maintaining theemulsion state of the LBM, adult stem cells are co-cultured with theemulsion using standard stem cell culturing techniques. When the cellsare ready, the entire composition is loaded into a catheter forpercutaneous delivery to a human patient in need of tissue regenerationat a site of defective or absent myocardium. The emulsion with theco-cultured cells is delivered to the patient: a percutaneous catheteris loaded with the emulsion and directed to the site of the myocardiumin need of tissue regeneration using sonographic or radiographicimaging. Upon contact with the site, the emulsion is released and thecatheter is withdrawn. The tissue regeneration process is monitored bysonography for several weeks or months post-delivery of the emulsion.

Example 3

An injectable emulsion of decellularized immunogenic stomach submucosa(SS) is prepared using standard known techniques. An aliquot ofglycosaminoglycan (GAG) protein is covalently linked to some of themolecules of the matrix emulsion using standard covalent linkingprocedures for proteins. While maintaining the emulsive state of the SS,bone marrow progenitor cells are co-cultured with the emulsion usingstandard progenitor cell culturing techniques. An aliquot oftransforming growth factor protein is added to the co-culturingcomposition before delivery to the human in need of myocardial tissueregeneration. The emulsion complete with cells and proteins is loadedinto a percutaneous catheter which is directed to the site of themyocardium in need of tissue regeneration using sonographic orradiographic imaging. Upon contact with the site, the emulsion isreleased, and the catheter is withdrawn. The tissue regeneration processis monitored by sonography for several weeks or months post-delivery ofthe emulsion.

The preceding merely illustrates the principles of the invention. Itwill be appreciated that those skilled in the art will be able to devisevarious arrangements which, although not explicitly described or shownherein, embody the principles of the invention and are included withinits spirit and scope.

Furthermore, all examples and conditional language recited herein areprincipally intended to aid the reader in understanding the principlesof the invention and the concepts contributed by the inventors tofurthering the art, and are to be construed as being without limitationto such specifically recited examples and conditions.

Moreover, all statements herein reciting principles, aspects, andembodiments of the invention as well as specific examples thereof, areintended to encompass both structural and functional equivalentsthereof.

Additionally, it is intended that such equivalents include bothcurrently known equivalents and equivalents developed in the future,i.e., any elements developed that perform the same function, regardlessof structure. The scope of the present invention, therefore, is notintended to be limited to the exemplary embodiments shown and describedherein. Rather, the scope and spirit of present invention is embodied bythe appended claims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassedwithin the invention. The upper and lower limits of these smaller rangesmay independently be included or excluded in the range, and each rangewhere either, neither or both limits are included in the smaller rangesis also encompassed within the invention, subject to any specificallyexcluded, limit in the stated range. Where the stated range includes oneor both of the limits, ranges excluding either or both of those includedlimits are also included in the invention.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. It must be noted that as usedherein and in the appended claims, the singular forms “a”, “an”, and“the” include plural referents unless the context clearly dictatesotherwise.

All publications cited are incorporated in their entirety. Suchpublications are provided solely for their disclosure prior to thetiling date of the present application. Nothing herein is to beconstrued as an admission that the present invention is not entitled toantedate such publication by virtue of prior invention. Further, thedates of publication provided may be different from the actualpublication dates which may need to be independently confirmed.

What is claimed is:
 1. A method for regenerating damaged or diseasedmammalian tissue, comprising the steps of: providing a sheet structurecomprising acellular dermal mammalian tissue, said acellular dermalmammalian tissue comprising extracellular matrix (ECM), said ECMcomprising collagen type I, collagen type III, proteoglycans,transforming growth factor beta (TGF-β) and fibroblast growth factor-2(FGF-2), said acellular dermal mammalian tissue further comprising asupplemental bioactive component comprising an exogenously added cellselected from the group consisting of an embryonic stem cell, amesenchymal cell, and a hematopoietic stem cell, said exogenously addedcell being linked to said ECM, wherein said exogenously added cellinteracts with at least one molecule in said ECM, whereby, when saidacellular dermal mammalian tissue is disposed proximate to damagedmammalian tissue, said acellular dermal mammalian tissue inducesangiogenesis; and delivering said sheet structure to said damaged ordiseased mammalian tissue, wherein said sheet structure inducesregeneration of new mammalian tissue.
 2. The method of claim 1, whereinsaid damaged or diseased mammal tissue comprises damaged or diseasedcardiovascular tissue.
 3. The method of claim 2, wherein saidexogenously added cell comprises a cell selected from the groupconsisting of a neonatal cardiomyocyte, a fetal cardiomyocyte and amyofibroblast.
 4. A method for regenerating damaged or diseasedmammalian tissue, comprising the steps of: providing a sheet structurecomprising acellular dermal mammalian tissue, said acellular dermalmammalian tissue comprising extracellular matrix (ECM), said ECMcomprising collagen type I, collagen type III, proteoglycans,transforming growth factor beta (TGF-β) and fibroblast growth factor-2(FGF-2), said acellular dermal mammalian tissue further comprising asupplemental bioactive component comprising an exogenously added nucleicacid, said exogenously added nucleic acid being linked to said ECM,wherein said exogenously added nucleic acid interacts with said ECM,whereby, when said acellular dermal mammalian tissue is disposedproximate to damaged mammalian tissue, said acellular dermal mammaliantissue induces angiogenesis; and delivering said sheet structure to saiddamaged or diseased mammalian tissue, wherein said sheet structureinduces regeneration of new mammalian tissue.
 5. The method of claim 4,wherein said damaged or diseased mammal tissue comprises damaged ordiseased cardiovascular tissue.
 6. The method of claim 5, wherein saidexogenously added cell comprises a cell selected from the groupconsisting of an embryonic stem cell, a mesenchymal cell, ahematopoietic stem cell, a neonatal cardiomyocyte, a fetal cardiomyocyteand a myofibroblast.
 7. The method of claim 4, wherein said exogenouslyadded nucleic acid comprises DNA.
 8. The method of claim 4, wherein saidexogenously added nucleic acid comprises cDNA.
 9. The method of claim 4,wherein said exogenously added nucleic acid comprises RNA.
 10. Themethod of claim 9, wherein said RNA comprises mRNA.
 11. The method ofclaim 9, wherein said RNA comprises tRNA.
 12. The method of claim 9,wherein said RNA comprises rRNA.
 13. The method of claim 9, wherein saidRNA comprises synthetic RNA.